Ultra-Low Pressure Digital Sensor: SM9333/SM9336 Series Differential Pressure Sensors
Ultra-Low Pressure Digital Sensor: SM9333/SM9336 Series Differential Pressure Sensors
Digital Sensor
SM9333/SM9336 Series
Differential Pressure Sensors
FEATURES
• Pressure ranges: 125 and 250 Pa Differential
• Accuracy after Autozero: < 1%FS
• 16 bit I2C Digital interface
• Pressure calibrated and temperature compensated output
• Compensated temperature range: -20 to 85oC
DESCRIPTION
The SM9333/SM9336 are digital, ultra-low pressure sensors offering Combining the pressure sensor with a signal-conditioning ASIC in a
state-of-the-art MEMS pressure transducer technology and CMOS single package simplifies the use of advanced silicon micro-machined
mixed signal processing technology to produce a digital, fully pressure sensors. The pressure sensor can be mounted directly on a
conditioned, multi-order pressure and temperature compensated standard printed circuit board and a high level, calibrated pressure
sensor in JEDEC standard SOIC-16 package with a dual vertical signal can be acquired from the digital interface. This eliminates the
porting option. It is available in a differential pressure configuration. need for additional circuitry, such as a compensation network or
microcontroller containing a custom correction algorithm.
The total accuracy after board mount and system level autozero is
less than 1%FS. The excellent warmup behavior and long term The SM9333/SM9336 are shipped in sticks or tape & reel.
stability further assures its expected performance over the life of the
part.
Medical Industrial
Sleep Apnea HVAC
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Notes:
a. Tested on a sample basis.
b. Clean, dry air compatible with wetted materials. Wetted materials include silicon, glass, RTV (silicone), gold, aluminum, copper, nickel,
palladium, epoxy, stainless steel and plastic (mold compound).
c. Proof pressure is defined as the maximum pressure to which the device can be taken and still perform within specifications after
returning to the operating pressure range.
d. Burst pressure is the pressure at which the device suffers catastrophic failure resulting in pressure loss through the device.
2. ESD
No. Description Symbol Minimum Maximum Units
2.1 ESD HBM Protection at all Pins VESD(HBM) -2 2 kV
3. External Components
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3 High level input voltage at SDA, SCL VIN,I2C,hi 0.8 * VVDD VVDD+0.3 V
Notes:
b. Clean, dry air compatible with wetted materials.
7 I2C Interface
No. Description Condition Symbol Min. Typ. Max. Units
1 SDA output low voltage* ISDA = 3 mA VSDA,OL 0 0.4 V
2 Low-to-High transition threshold* pins SA0, SCL VSDA,LH 0.5 0.6 0.7 VDD
3 High-to-Low transition threshold* pins SA0, SCL VSDA,HL 0.3 0.4 0.5 VDD
5 Bus free time between a START and STOP condition* tBUSF 1300 ns
8. Qualification Standards
REACH Compliant
RoHS Compliant
PFOS/PFOA Compliant
For qualification specifications, please contact Sales at sales@si-micro.com
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9. Package Reference
SOIC-16 (C) Vertical Package Dimensions
Notes:
• All dimensions in units of [mm]
• Moisture Sensitivity Level (MSL): Level 3
• Clean, dry air compatible with wetted materials. Wetted materials include : Wetted materials include silicon, glass, RTV (silicone), gold,
aluminum, copper, epoxy and mold compound.
• Tolerance on all dimensions ±0.13 mm unless otherwise specified.
• [B] is tube connected to bottom side of sensor die.
• [T] is tube connected to top side of sensor die. Topside pressure is positive pressure. An increase in topside pressure will result in an
increase in sensor output
• Bottom plate is stainless steel
• Robust JEDEC SOIC-16 package for automated assembly
• Manufactured according to ISO9001 , ISO14001 and ISO/TS 16949 standards
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Package Labeling
Pin No. Pin Function
1 NC (No Connect)
2 NC
3 NC
4 NC
5 VSS
6 VDD
7 NC
8 NC
9 NC
10 SDA
11 SCL
12 NC
13 GND (ASIC Test Pin)
14 NC
15 NC
16 NC
NOTES:
• Do not connect to NC pins
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Package Pin-Out
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*Zero pressure accuracy tested at 30 oC and 3.3V. Measured after HTOL (at
105 oC and 5.5V) at 168, 500 and 1000 hrs. Not tested in production
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13.1 Overview
The SM9x3x series is a high precision, factory calibrated differential pressure sensor for ultra low pressure measurements. It combines a
low pressure MEMS die with a 16 bit ASIC, utilizing DSP for multi dimensional polynomial error correction. The calibrated pressure output
data is available via digital data interface (I2C). Status information on the sensor integrity and unique serial number are accessible via this
digital interface.
The pressure sensor device is calibrated in the end-of-line production test over the specified Pmin to Pmax pressure range (see Section 4).
The output code at Pmin is nominally -26,215 and at Pmax it is nominally 26,214. This allows the sensor to still operate monotically outside
its nominal range till the maximum (or minimum) counts are reached. An example for a 250 differential SM9336-BCE-S-250-000 is given in
the graph below
The equation below converts p%FS to actual calibrated pressure units pp-unit with pmin and pmax as specified in section 4
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The digital data interface allows to set it into Sleep Mode using a specific command (Enter Sleep Mode), which ensures very low
consumption (IVDD,SM) of typically less than 10 µA. Of course, in Sleep Mode no pressure data is acquired.
For the I2C command to send the sensor into Sleep Mode see 13.6. To wake-up the sensor to normal operation, the clock input SCL shall be
toggled (a rising edge at SCL will wake-up the device).
Bridge Diagnostics
An integrated bridge diagnostic circuit supervises the resistive pressure sensor to detect any of the faults as follows:
• Sensor faults:
• Short of any of the four bridge resistors of the pressure sensor
• Interruption of any of the four of bridge resistors
• Wiring faults:
• Open connection of any of the bridge supply or signals
• Wrong connection of any sensor bridge terminal to either ground or bridge supply
The MEMS sensor bridge diagnostics are active permanently (true background diagnostics) and in case of an error the bridge check fail
event is indicated by setting the bit bc_fail in the internal STATUS register.
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• Random write: Sets a memory address and writes data to consecutive memory addresses of the device starting at the set memory
address.
• Random read: Sets a memory address and reads data from consecutive memory addresses of the device starting at the set memory
address.
• Read last: Reads data from the device starting at the last memory address set by the master. This facilitates repeated reading of the
same memory addresses without transmitting a memory address first.
All reads/writes must start at word aligned addresses (i.e. LSB of memory address equals 0) and read/write an even number of bytes.
The two different frame types - standard EEPROM (without CRC) or CRC protected - are shown in the next two figures.
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The memory address field sets the byte address of the first memory location to be read from or written to. Only 16-bit-word aligned
reads/writes are supported, i.e. the LSB of memory address has to be zero always. The read/write data is transferred MSB first, low byte
before high byte.
The length field (bits[7:4]) required for CRC protected frames specifies the number of data bytes to be transferred decremented by one,
i.e. a value of 0001b corresponds to two bytes. All frames must transfer an even number of bytes. The maximum length for CRC protected
read/write frames is 16/4 bytes. For unprotected frames the length is unlimited.
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The CRC4 and CRC8 for redundancy check are computed in the same bit and byte order as the transmission over the bus. The polynomials
employed are:
If a CRC errors occurs, then the event bit com_crc_error in the STATUS register will be set.
The command sequence following describes an unprotected Read command (without CRC) of 3 subsequent 16-bit words starting at
memory address 0x2E to read the corrected IC temperature, corrected pressure signal, and (synchronized) status bits of the sensor.
Random Read:
Byte # 0 1 2 3 4 5 6 7 8
SBM
0xD8 0x2E 0xD9
(sent by master)
slave slave
address 6C memory address 6C
SBM comment
+ LSB = 0 address + LSB = 1
for Write for Read
SBS
0xF2 0x7D 0xEA 0x82 0x1E 0x00
(sent by sensor)
sync‘ed
DSP_T DSP_S sync‘ed
DSP_T DSP_S Status
SBS comment (Lo-Byte) (Lo-Byte) Status
(Hi-Byte) (Hi-Byte) (b7 - b0)
ad. 0x2E ad. 0x30 (b15 - b8)
ad. 0x32
The following sequence writes one 16-bit word to address 0x22. This will copy 0x6C32 into the command register CMD to move the
component to Sleep Mode.
Random Write:
Byte # 0 1 2 3
SBM
0xD8 0x22 0x32 0x6C
(sent by master)
slave address 6C
Lo-Byte written to Hi-Byte written to
SBM comment + LSB = 0 memory address
CMD[7:0] CMD[15:8]
for Write
SBS
(sent by sensor)
SBS comment
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The next command sequence describes a CRC protected Read command of 3 subsequent 16-bit words starting at memory address 0x2E.
Byte # 0 1 2 3 4 5 6 7 8 9 10
SBM
(sent by 0xDA 0x2E 0x5B 0xDB
master)
slave slave
address 3: length address
memory
SBM comment 6D = 4Byte 6D
address
+ LSB = 0 B: CRC4 + LSB = 1
for Write for Read
SBS
0xF2 0x7D 0xEA 0x82 0x1E 0x00 0x65
(sent by sensor)
sync‘ed
DSP_T DSP_S sync‘ed
DSP_T DSP_S Status CRC8
SBS comment (Lo-Byte) (Lo-Byte) Status
(Hi-Byte) (Hi-Byte) (b7 - b0) (calc'd)
ad. 0x2E ad. 0x30 (b15 - b8)
ad. 0x32
The next example describes a Write of one 16-bit word (contents 0xCF9E) with CRC protection to address 0x36 to clear events in the
STATUS register.
Byte # 0 1 2 3 4 5
SBM
0xDA 0x36 0x16 0x9E 0xCF 0xA1
(sent by master)
slave address 6D 1: length = 2Byte STATUS
STATUS CRC8
SBM comment + LSB = 0 memory address 6: CRC4 (Lo-Byte)
(Hi-Byte) (calculated)
for Write ad. 0x36
SBS
(sent by sensor)
SBS comment
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Command register:
0x22 CMD
bits name default rw description
Writing to this register controls the state of the SM9x3x device.
Temperature register:
0x2E DSP_T
bits name default rw description
Corrected temperature measurement value of the sensor.
15:0 dsp_t r Whenever this register is updated with a new measurement the STATUS.dsp_t_up event
bit is set.
Pressure register:
0x30 DSP_S
bits name default rw description
corrected pressure measurement value of the sensor.
15:0 dsp_s r Whenever this register is updated with a new measurement the STATUS.dsp_s_up event
bit is set.
The registers DSP_T and DSP_S contain invalid data after power-up until the first temperature and pressure values have been measured by
the device and transferred to these registers. In case a NVM CRC error occurred, the DSP_T and DSP_S registers would never be updated.
Thus, after power up it is necessary to wait until the STATUS.dsp_s_up and dsp_t_up bits have been set at least once before using the
temperature or pressure data. It is not sufficient to wait just for a fixed time delay.
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0x32 STATUS_SYNC
bits name default rw type description
0 idle 0 rw status STATUS.idle
1 - reserved - 0 rw event reserved
2 - reserved - 0 rw event reserved
3 dsp_s_up 0 rw event when DSP_S is read STATUS.dsp_s_up is copied here
4 dsp_t_up 0 rw event when DSP_T is read STATUS.dsp_t_up is copied here
5 - reserved - 0 rw status reserved
6 - reserved - 0 rw status reserved
7 bs_fail 0 rw event STATUS.bs_fail
8 bc_fail 0 rw event STATUS.bc_fail
9 - reserved - 0 rw event reserved
10 dsp_sat 0 rw status STATUS.dsp_sat
11 com_crc_error 0 rw event STATUS.com_crc_error
12 - reserved - 0 rw status reserved
13 - reserved - 0 rw status reserved
14 dsp_s_missed 0 rw event STATUS.dsp_s_missed
15 dsp_t_missed 0 rw event STATUS.dsp_t_missed
The bits STATUS_SYNC[15:5,0] are identical to the bits STATUS[15:5,0].
The bits STATUS_SYNC[4:3] are copied from the STATUS register when the corresponding DSP registers are read. First reading the DSP
registers and then STATUS_SYNC ensures that both values are consistent to each other.
The synchronized status STATUS_SYNC register can be used to continuously poll the pressure, temperature and status of the device with
a single read command by reading three 16 bit words starting at address 0x2E. By evaluating STATUS_SYNC.dsp_t_up and
STATUS_SYNC.dsp_s_up it can be determined if the values in DSP_T and DSP_S acquired during the same read contain recently updated
temperature or pressure values.
Status register:
0x36 STATUS
bits name default rw type1 description
0: chip in busy state
0 idle 0 rw status
1: chip in idle state
1 - reserved - 0 rw event reserved
2 - reserved - 0 rw event reserved
1: DSP_S register has been updated.
3 dsp_s_up 0 rw event
Cleared when DSP_S is read
1: DSP_T register has been updated.
4 dsp_t_up 0 rw event
Cleared when DSP_T is read.
5 - reserved - 0 rw status reserved
6 - reserved - 0 rw status reserved
7 bs_fail 0 rw event 1: bridge supply failure occurred
8 bc_fail 0 rw event 1: sensor bridge check failure occurred
9 - reserved - 0 rw event reserved
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0x36 STATUS
bits name default rw type1 description
1: a DSP computation leading to the current DSP_T or DSP_S values
10 dsp_sat 0 rw status
was saturated to prevent overflow
11 com_crc_error 0 rw event 1: communication CRC error
12 - reserved - 0 rw status reserved
13 - reserved - 0 rw status reserved
14 dsp_s_missed 0 rw event 1: dsp_s_up was 1 when DSP_S updated
15 dsp_t_missed 0 rw event 1: dsp_t_up was 1 when DSP_T updated
1)
• "Event" type flags remain set until cleared by writing '1' to the respective bit position in STATUS register (not STATUS_SYNC). Writing
0xFFFF to the STATUS register will clear all event bits.
• "Status" type flag represents a condition of a hardware module of the IC and persists until the condition has disappeared.
0x50 SER0
bits name default rw description
0x50 SER1
bits name default rw description
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DOC # 40DS9302.02
SM9235, SM9333/SM9336 Series www.si-micro.com
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Authorized Distributor
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SM9333-BCE-S-125-000 SM9333-BCE-T-125-000 SM9336-BCE-T-250-000 SM9336-BCE-S-250-000